1. Field of the Invention
The present invention relates generally to a swirl chamber for an internal combustion engine and more specifically to an improved transfer port arrangement therefor.
2. Description of the Prior Art
A previously proposed arrangement shown in FIGS. 1 and 2 of the drawings (disclosed in Prepublished Japanese Patent application No. 51-105509) includes an auxiliary transfer port 1 for transferring a fraction of the fuel injected into the swirl chamber 2 in an unvapourized state into the main combustion chamber 3 for the purposes of improving the fuel distribution between the two chambers and reducing the formation of NOx and the like. However, this arrangement has suffered from the drawback that the unvapourized fuel which passes through the auxiliary port 1 tends to cool the mouth piece 4 of the swirl chamber 2 in the immediate vicinity of the auxiliary transfer port and induces a temperature differential in the zone 5 located between said auxiliary transfer port 1 and a relatively hot main transfer port 6 through which hot combustion gases pass during the expansion phase of the engine. This temperature differential induces sufficient stress in the zone 5 to produce cracks and the like especially along the plane interconnecting the axes of the two ports.